The following recommendations for safely clearing ash from outdoor surfaces, including ornamental and edible plants, come from the Environmental Protection Agency, Oregon State University Extension Service and Waste Management.
Basic guidelines: Wait until air quality levels are safe for being outdoors. Close all windows and doors to your home before cleaning the ash outside. Protect your lungs and skin: if an N95 mask is not available use a double-thickness cloth mask, and wear long sleeves, long pants, shoes, and gloves. To minimize stirring the ash back into the air, lightly mist or spray the surface to be cleaned, using as little water as possible. Do not use leaf blowers; do not sweep dry ash. To avoid tracking in any ash particles, remove protective clothing and gear before going back inside your home.
Cleaning your entire property (including hardscape, garden plants, shrubs, and lawn) isn’t always necessary. A thin dusting of ash on plants (with green plant color still visible) isn’t likely to have long term effects on plant health before fall rains wash it away.
Patios and walkways: Concentrate on the most traveled areas. After lightly misting, use an old broom to clean patios and paths, and gently sweep ash off surfaces. You can also use a gentle low-pressure stream of water. In either case, don’t wash ash down the storm drain; instead, direct the rinse water or swept ash into low-traffic grassy or ornamental areas. This acts as a natural filter, especially once the rains come. Large amounts of ash can be lightly dampened then swept into a pile, bagged in plastic sacks, sealed and thrown away. Never deposit ash in recycling or green waste containers — it is only safe to put it in the trash receptacle.
Plants: The same precautions apply to ridding plant surfaces of ash. Focus on clearing heavier amounts of ash from food-producing plants and plants that you regularly come in contact with, such as those near windows, doors, or air handling units.
Edibles from your garden: Once properly cleaned, these should be safe to consume, as smoke and ash do not usually penetrate the protective skin covering fruits and vegetables.
However, according to the OSU College of Agricultural Sciences, “safety becomes more of an issue … if your garden has a heavy layer of ash or is located near a structure that burned. Burning buildings contain different toxins than a forest.”
OSU goes on to recommend that you “peel produce like tomatoes, apples, and root crops and strip the outer leaves of lettuces and other greens. For a more thorough cleaning, soak vegetables and fruits in a 10% white vinegar solution (1 cup vinegar to 9 cups water), which can lift soil particles off vegetables and fruits.”
Please be safe in your garden, but also, as soon as is feasible, enjoy the out of doors.
Plants and sunlight offer healing properties to humans.